Endoscopic-assisted transorbital extended orbital exenteration: A multi-institutional preclinical study.

BACKGROUND: Sinonasal malignancies with orbital invasion have dismal prognosis even when treated with orbital exenteration (OE). Sugawara et al. developed a surgical strategy called "extended-OE (EOE)," showing encouraging outcomes. We hypothesized that a similar resection is achievable under endoscopic guidance through the exenterated orbit (endoscopic-EOE). METHODS: The study was conducted in three institutions: University of Vienna; Mayo Clinic; University of Insubria; 48 orbital dissections were performed. A questionnaire was developed to evaluate feasibility and safety of each step, scoring from 1 to 10, ("impossible" to "easy," and "high risk" to "low risk," respectively), most likely complication(s) were hypothesized. RESULTS: The step-by-step technique is thoroughly described. The questionnaire was answered by 25 anterior skull base surgeons from six countries. Mean, median, range, and interquartile range of both feasibility and safety scores are reported. CONCLUSIONS: Endoscopic-EOE is a challenging but feasible procedure. Clinical validation is required to assess real-life outcomes.

Minimal Detectable Bone Fracture Gaps in CT Images and Digital Three-Dimensional (3D) Radii Models.

Knowledge of the minimal detectable bone fracture gap is essential in three-dimensional (3D) models, particularly in pre-operative planning of osteosynthesis to avoid overlooking gaps. In this study, defined incisions and bony displacements ranging from 100 to 400 µm were created in diaphyseal radii in 20 paired forearm specimens and verified with light microscopy. The specimens were scanned utilizing different computed tomography (CT) technologies/scanners, specimen positionings, scan protocols, image segmentations, and processing protocols. Inter- and intra-operator variabilities were reported as coefficient kappa. In CT images, fracture gaps of 100 µm and bone lamellae of 300 µm and 400 µm width were identified at a rate of 80 to 100%, respectively, independent of the investigated settings. In contrast, only 400µm incisions and bony displacements were visible in digital 3D models, with detection rates dependent on CT technology, image segmentation, and post-processing algorithm. 3D bone models based on state-of-the-art CT imaging can reliably visualize clinically relevant bone fracture gap sizes. However, verification of fractures to be surgically addressed should be verified with the original CT image series.

Effect of hot water maceration, rehydration, and soft tissue presence on 3D geometry of bone.

PURPOSE: In forensic medicine, maceration is often essential for examining bone surfaces, serving purposes such as identifying cut marks, making geometric measurements, and determining the victim's age. While hot water maceration removes soft tissue effectively, it is known to cause bone surface shrinkage. This raises the question of whether this effect is permanent or if it can be partially reversed through rehydration, considering the presence of soft tissue. METHODS: Computed tomography (CT) scans were conducted on the radii of 20 paired human anatomic forearm specimens. Subsequently, the radii were extracted, macerated in 60 °C water, CT-scanned in an air environment, rehydrated, re-implanted into the forearms, and CT-scanned again. RESULTS: Maceration resulted in a mean shrinkage of 0.12 mm on the outer bone surface. This shrinkage was nearly fully recoverable for the diaphysis after rehydration and accounting for soft tissue surrounding the bone. In contrast, the epiphysis showed permanent shrinkage, likely due to the loss of small bone fragments. Analysis of the inner bone surface indicated a smaller effect, but with significant standard deviations, especially for the epiphysis, possibly related to the less well-defined nature of the inner bone surface. CONCLUSION: The epiphyseal surface of hot water-macerated bone will, on average, be approximately 0.15 mm deflated and cannot retain the original surface. On the other hand, the diaphyseal surface is less affected and can be nearly completely restored after rehydration and accounting for soft tissue surrounding the bone.

The mylohyoid line is highly variable but does not affect the microarchitecture of the edentulous alveolar bone - an anatomical micro-CT study.

OBJECTIVES: To evaluate in the absence of teeth the variability of the mylohyoid line (ML), the microarchitecture of the adjacent bone, and whether the variable prominence/width of the ML is associated with the quality of the adjacent bone. METHODS: µCT scans of 28 human mandibles from anatomical specimens were analyzed. The following parameters were assessed in four edentulous areas (first and second premolar (PM), first, second, and third molar (M1/2/3)): ML width, cortical thickness (CtTh), average cortical- (Avg.Ct.BV/TV), and trabecular bone volume fraction (Avg.Tb.BV/TV). RESULTS: The ML width increased from the PM towards the M2 region, which also showed the highest variance (range: 0.4-10.2 mm). The CtTh showed a decrease in the M3 region, while Avg.Ct.BV/TV and Avg.Tb.BV/TV hardly differed among the regions. In the multivariable model on the effect of the various parameters on the ML width, only gender and tooth region were significant. Specifically, male specimens were associated with a wider ML width compared to female specimens and the M2 region was associated with a wider ML width compared to the other tooth regions. CONCLUSION: The ML width was not associated with the cortical and trabecular bone quality in the adjacent bone, while gender and tooth region had a significant effect. Specifically, the ML width was lower in female, but peaked in the M2 region with a median width of 3-4 mm. CLINICAL RELEVANCE: From a clinical point of view, it was confirmed that the ML is in general a highly variable structure, especially in the M2 region, but the ML width does not allow any conclusions on the bone quality. Altogether, this underlines the need for an individual and accurate diagnostic prior to any surgical intervention.

Three-Dimensional Osseointegration Patterns of Cementless Femoral Stems: An ex Vivo Study with High-Resolution Imaging and Histological Evaluation.

BACKGROUND: Osseointegration is essential for the long-term survival of cementless femoral stems and is dependent on periprosthetic bone quality and correct implantation technique. The aim of this study was to evaluate the 3-dimensional long-term fixation patterns of, and bone microarchitecture around, cementless hip stems. METHODS: Four specimens with varying degrees of bone quality and fixation characteristics from body donors who had received Alloclassic Zweymüller hip stems during their lifetime (mean time in situ at the time of death: 12.73 years) were evaluated with use of radiographs, high-resolution computed tomography (CT) scans, and hard-tissue histology. The CT voxel size was 85 µm, and the following parameters were calculated: total bone volume, total bone volume fraction, trabecular bone volume, trabecular bone volume fraction, cortical bone volume, cortical bone volume fraction, and cortical thickness. Bone-implant contact and canal fill index values for each Gruen zone of the specimens were calculated with use of histological samples. RESULTS: Femoral stems with apparently good cortical contact on clinical radiographs showed higher values for cortical bone volume, trabecular bone volume, and cortical thickness in the high-resolution CT analysis than femoral stems with apparently weak cortical contact on clinical radiographs. Based on the histological evaluation, the mean bone-implant contact ranged from 22.94% to 57.24% and the mean canal fill index ranged from 52.33% to 69.67% among the specimens. CONCLUSIONS: This study demonstrated different osseointegration patterns of cementless femoral stems on the basis of radiographs, high-resolution CT scans, and histological evaluation. Femora with high cortical bone volume and cortical thickness were associated with higher canal fill indices, whereas femora with low cortical bone volume and cortical thickness had lower canal fill indices and showed a characteristic corner-anchorage pattern. CLINICAL RELEVANCE: Osseointegration patterns and thus the long-term survival of cementless femoral stems are dependent on cortical bone volume and cortical thickness.

Accuracy Analysis of 3D Bone Fracture Models: Effects of Computed Tomography (CT) Imaging and Image Segmentation.

The introduction of three-dimensional (3D) printed anatomical models has garnered interest in pre-operative planning, especially in orthopedic and trauma surgery. Identifying potential error sources and quantifying their effect on the model dimensional accuracy are crucial for the applicability and reliability of such models. In this study, twenty radii were extracted from anatomic forearm specimens and subjected to osteotomy to simulate a defined fracture of the distal radius (Colles' fracture). Various factors, including two different computed tomography (CT) technologies (energy-integrating detector (EID) and photon-counting detector (PCD)), four different CT scanners, two scan protocols (i.e., routine and high dosage), two different scan orientations, as well as two segmentation algorithms were considered to determine their effect on 3D model accuracy. Ground truth was established using 3D reconstructions of surface scans of the physical specimens. Results indicated that all investigated variables significantly impacted the 3D model accuracy (p < 0.001). However, the mean absolute deviation fell within the range of 0.03 ± 0.20 to 0.32 ± 0.23 mm, well below the 0.5 mm threshold necessary for pre-operative planning. Intra- and inter-operator variability demonstrated fair to excellent agreement for 3D model accuracy, with an intra-class correlation (ICC) of 0.43 to 0.92. This systematic investigation displayed dimensional deviations in the magnitude of sub-voxel imaging resolution for all variables. Major pitfalls included missed or overestimated bone regions during the segmentation process, necessitating additional manual editing of 3D models. In conclusion, this study demonstrates that 3D bone fracture models can be obtained with clinical routine scanners and scan protocols, utilizing a simple global segmentation threshold, thereby providing an accurate and reliable tool for pre-operative planning.

First standardized assessment of perforators and perforasomes of the occipital artery - An anatomical study.

BACKGROUND: Flaps have become an integral part of plastic and reconstructive surgery. The robust blood supply of such flaps is a prerequisite to reduce flap failure. Despite the reported versatility of the occipital flap, comprehensive anatomical studies on its perforators and perforasomes are lacking. Hence, we examined the perforators originating from the occipital artery and their associated perforasomes, aiming to fill this knowledge gap for reconstructive surgery techniques. METHODS: 39 of 40 occipital arteries of 20 fresh anatomical head specimens were dissected. Perforators with a least an outer diameter of 0.50 mm were identified and injected with dye to color their respective perforasomes. Location and size of the colored skin areas were determined as well as the location of their perforators were documented and analyzed. RESULTS: In total, 183 perforators were found and described. The mean diameter of these vessels was 0.88 ± 0.27 mm (0.5-2.1 mm). The mean area of the perforasomes was 1288.26 ± 662.51 mm2 (144.60-3890.60 mm2). They were localized over the whole nuchal and occipital area. Lastly, perforator diameters were significantly associated with the size of their resulting perforasomes. CONCLUSION: This study is the first comprehensive overview of perforators and associated perforasomes of the occipital artery on a respectable amount of specimen. The arterial supply of big portions of the occipital and nuchal area is provided solely by the perforators of the occipital artery. For flap surgery, perforator diameter is a crucial detail to be considered in the decision-making process.

Anatomical Variation of Infrapatellar Innervation Determines Clinical Risk of Infrapatellar Neuropathy.

BACKGROUND: Infrapatellar neuropathy arises from traumatic, iatrogenic, or compression injury to the infrapatellar branch (IB) of the saphenous nerve. The risk of infrapatellar neuropathy has been shown to depend on the IB's anatomical course. The infrapatellar branch of the saphenous nerve (ISBN) has been discovered to take varying courses, and the IB can emerge directly from the femoral nerve. The variety of the IBSN's courses and the prevalence of cases involving the infrapatellar branch of the femoral nerve (IBFN) call the uniform IB course described in textbooks into question. OBJECTIVES: In this study, we aim to identify sites of IB emergence and their anatomical relations and evaluate them for their risk of neuropathy. STUDY DESIGN: The study is an anatomical prospective pilot study. SETTING: The setting is a single-center cadaveric study performed at the anatomical institute of the Medical University of Vienna. METHODS: Twenty-two anatomical specimens were evaluated for the relationship of their IBs to anatomical risk sites. The subsartorial course, distal sartorial penetration, and the crossing of the medial femoral epicondyle were assessed. The measurements and relations of the IB were determined with callipers and assessed by computational modelling. RESULTS: Nine IBs originated from the saphenous nerve, 11 originated from the femoral nerve, and 2 originated from both. The subsartorial course was most frequent in IBs of saphenous origin. Penetrating and profound distal sartorial relations correlated moderately with emergence type and were highest in the saphenous group. The crossing of the medial femoral epicondyle was the most common relation of IBs that emerged femorally. LIMITATIONS: The study's limitations were the low number of cadavers to examine and the confining of the exploration of knee extension to anatomical specimens that restricted an inferential analysis. CONCLUSION: Infrapatellar innervation can emerge from the saphenous nerve, the femoral nerve, or a combination of both, and the origin of the innervation determines the clinical risk for infrapatellar neuropathy. While innervation from the IBSN may lead to compression at the subsartorial course, distal sartorial penetration, and the crossing of the medial femoral epicondyle, innervation from the IBFN carries reduced anatomical risk for infrapatellar neuropathy.

Dimensional accuracy and precision and surgeon perception of additively manufactured bone models: effect of manufacturing technology and part orientation.

BACKGROUND: Additively manufactured (AM) anatomical bone models are primarily utilized for training and preoperative planning purposes. As such, they must meet stringent requirements, with dimensional accuracy being of utmost importance. This study aimed to evaluate the precision and accuracy of anatomical bone models manufactured using three different AM technologies: digital light processing (DLP), fused deposition modeling (FDM), and PolyJetting (PJ), built in three different part orientations. Additionally, the study sought to assess surgeons' perceptions of how well these models mimic real bones in simulated osteosynthesis. METHODS: Computer-aided design (CAD) models of six human radii were generated from computed tomography (CT) imaging data. Anatomical models were then manufactured using the three aforementioned technologies and in three different part orientations. The surfaces of all models were 3D-scanned and compared with the original CAD models. Furthermore, an anatomical model of a proximal femur including a metastatic lesion was manufactured using the three technologies, followed by (mock) osteosynthesis performed by six surgeons on each type of model. The surgeons' perceptions of the quality and haptic properties of each model were assessed using a questionnaire. RESULTS: The mean dimensional deviations from the original CAD model ranged between 0.00 and 0.13 mm with maximal inaccuracies < 1 mm for all models. In surgical simulation, PJ models achieved the highest total score on a 5-point Likert scale ranging from 1 to 5 (with 1 and 5 representing the lowest and highest level of agreement, respectively), (3.74 ± 0.99) in the surgeons' perception assessment, followed by DLP (3.41 ± 0.99) and FDM (2.43 ± 1.02). Notably, FDM was perceived as unsuitable for surgical simulation, as the material melted during drilling and sawing. CONCLUSIONS: In conclusion, the choice of technology and part orientation significantly influenced the accuracy and precision of additively manufactured bone models. However, all anatomical models showed satisfying accuracies and precisions, independent of the AM technology or part orientation. The anatomical and functional performance of FDM models was rated by surgeons as poor.

Hotspots of facial artery perforators and perforasomes for easier flap guidance: An anatomical study.

BACKGROUND: The facial artery perforator flap is a valuable alternative for reconstruction of small to medium defects in the central midface and provide pleasing cosmetic results, allowing reconstruction in a one-stage procedure. Since Doppler ultrasound is not applicable to distinguish perforator from source artery, anatomical studies are needed to identify perforator areas along the course of the facial artery. METHODS: Twenty facial arteries of 10 fresh anatomical head specimens were dissected. All perforators with an outer diameter of at least 0.50 mm were identified and injected with dye to color their respective vascular territories. Size and location of colored skin territories as well as the location of its perforators were documented and statistically analyzed. RESULTS: In total, 89 perforators were identified. The average number of perforators per facial artery was 4.45±1.15. The mean outer diameter of the perforator at the origin of the facial artery was 0,65±0.14 mm. The mean size of the colored skin territories was 577.57±488.81 mm2. Perforator diameters were significantly associated with the size of its resulting perforasomes. Furthermore, perforators mostly originated in two specific areas: 3.5 cm lateral and caudal and 4.5 cm lateral and 5.5 cm caudal of the anterior nasal spine. CONCLUSION: This study provides evidence of two predominant locations of emergence of facial artery perforators. Additionally, the significant correlation between perforator size and its appendant perforasomes as well as their location with reference to the anterior nasal spine as relevant osseous landmarks helps surgeons in decision making for flap design and surgery.

The Evolution of Sinus Tarsi Syndrome-What Is the Underlying Pathology?-A Critical Review.

Background and Objectives: Sinus tarsi syndrome (STS) is defined as pain located at the lateral opening of the tarsal sinus. The exact etiology of sinus tarsi syndrome is not completely understood. Some do not believe it to be a true pathology. This review aims to clarify the definition of sinus tarsi syndrome to better understand the underlying pathologies. We further propose an algorithm to evaluate sinus tarsi pain and provide advice for consecutive treatment options. Design: This is a narrative review. By searching PubMed, the available current literature was reviewed. Articles were critically analyzed to determine the pathoanatomy, biomechanics, and etiology of sinus tarsi pain. Algorithms for clinical evaluation, diagnosis, and treatment were also recorded. Finally, the authors approach to evaluating and treating sinus tarsi pain was included in this review. Results: Reviewing the available literature, STS seems to be a catch-all phrase used to describe any pain in this anatomic region. Many causes of sinus tarsi pain were listed, including impingement, subtalar instability, and many other pathologies around the ankle. Conclusions: A thorough evaluation of patients presenting with pain in the sinus tarsi or instability of the hindfoot is essential to determining the underlying cause. When the cause of pain is still not clear after clinical exam and radiologic assessment, subtalar arthroscopy can be helpful as both a diagnostic and treatment tool. We propose that the term of STS should be avoided and that a more accurate diagnosis be used when possible. Once a diagnosis is made, appropriate treatment can be initiated.

Peroneus tertius revisited: The morphological variability of the bifurcated peroneus tertius insertion - An anatomical study.

BACKGROUND: The peroneus tertius muscle (PT) is one of the extensor muscles of the lower leg, often described as a variable separation from the extensor digitorum longus muscle (EDL). According to literature it has six different types of insertion, one of them (Olewnik Type IV) having two tendons inserting to the fifth metatarsal bone (FMTB). Morphometric data about this type of insertion is sparse, especially the relation between the two tendons, albeit the PT is suspected to contribute to stress fractures of the FMTB. Therefore, we examined this type of insertion to give detailed information on the tendons, the insertion points and the respective relations. METHODS: We examined 27 lower extremities of embalmed human bodies (12 paired, 15 single sided; 12 right and 15 left) with a distinguishable PT with two tendons inserting to the FMTB (Olewnik IV). The specimens were obtained of an undergrad dissection program, which in turn obtained them from a body donation program. After dissection of the PT and photo documentation in situ, resection and measurement of morphological properties of the tendons were performed with the PT attached to the fifth metatarsal bone. RESULTS: Results of the respective measurements yielded a wide range of variation, especially in the insertion point of the anterior tendon on the fifth metatarsal and the relation between the two tendons, but with no significant difference between sides or sex, except for the length of the posterior tendon between sex. The distance between the base of the FMTB and posterior tendon varies from 0 to 9 mm, with one outlier at 24 mm (mean = 3.9 ± 4.8 mm), the distance between the insertions from 0 to 15 mm (mean = 4.7 ± 4.7 mm), resulting in how far of the FMTB the anterior tendon reaches varying from 17 to 60 mm (mean = 39.6 ± 11.5 mm) or 22-98% (mean = 64 ± 19%). CONCLUSION: Our findings give a detailed overview of the morphological features the PTT can have, when attached with two tendons to the FMTB. Especially the varying relationship between those two insertions and varying point of the anterior insertion are of interest, as they might support its complex role in the occurrence of fractures of the fifth metatarsal by providing different amounts of torsional stress and its tendons can be used as tendon-grafts.

The chemicals between us-First results of the cluster analyses on anatomy embalming procedures in the German-speaking countries.

Hands-on courses utilizing preserved human tissues for educational training offer an important pathway to acquire basic anatomical knowledge. Owing to the reevaluation of formaldehyde limits by the European Commission, a joint approach was chosen by the German-speaking anatomies in Europe (Germany, Austria, Switzerland) to find commonalities among embalming protocols and infrastructure. A survey comprising 537 items was circulated to all anatomies in German-speaking Europe. Clusters were established for "ethanol"-, formaldehyde-based ("FA"), and "other" embalming procedures, depending on the chemicals considered the most relevant for each protocol. The logistical framework, volumes of chemicals, and infrastructure were found to be highly diverse between the groups and protocols. Formaldehyde quantities deployed per annum were three-fold higher in the "FA" (223 L/a) compared to the "ethanol" (71.0 L/a) group, but not for "other" (97.8 L/a), though the volumes injected per body were similar. "FA" was strongly related to table-borne air ventilation and total fixative volumes ≤1000 L. "Ethanol" was strongly related to total fixative volumes >1000 L, ceiling- and floor-borne air ventilation, and explosion-proof facilities. Air ventilation was found to be installed symmetrically in the mortuary and dissection facilities. Certain predictors exist for the interplay between the embalming used in a given infrastructure and technical measures. The here-established cluster analysis may serve as decision supportive tool when considering altering embalming protocols or establishing joint protocols between institutions, following a best practice approach to cater toward best-suited tissue characteristics for educational purposes, while simultaneously addressing future demands on exposure limits.

A suture anchor-based repair technique for type IV jersey finger injuries: a biomechanical investigation.

The aim of this biomechanical investigation was to evaluate a repair technique for type IV FDP tendon avulsions using a suture anchor, addressing the bony and the tendinous aspect of this injury simultaneously. In 45 distal phalanges from human anatomical specimens the injury was simulated and repairs were performed with a suture anchor using an innovative technique, interosseous sutures and a combination of screws and an interosseous suture. Repetitive loading for 500 cycles simulated postoperative mobilization. Repairs were loaded to failure thereafter. Elongation of the tendon-suture complex, gap formation at the bone-bone contact line and at the bone-tendon insertion line, load at first noteworthy displacement (2 mm), load at failure and the mechanism of failure were assessed. The suture anchor technique was superior biomechanically considering load at failure (mean: 72.8 N), bony gap formation (mean: 0.1 mm) as well as tendinous gap formation (mean: 0.7 mm), implying a preferable stability of the repair. Overall, this study demonstrates good ex vivo mechanical stability for a proposed suture anchor repair technique for type IV FDP tendon avulsion injuries, which might enable early postoperative mobilization in patients. The technique's subcutaneous implant placement and low implant load are expected to reduce potential complications observed in other commonly used repair techniques. This approach warrants further evaluation in vivo.

Sensory Innervation of the Upper Eyelid and Its Implication for Upper Eyelid Surgery.

PURPOSE: Sensory alterations of the upper eyelid skin and eyelashes are frequently encountered after upper eyelid surgery. The objective of this study was to provide information on the exact course and distribution of sensory nerve fibers through the anatomic planes in the upper eyelid. METHODS: Ten formalin-fixed hemifaces were dissected. The nerve branches of the ophthalmic nerve in the upper eyelid were traced in an anterograde fashion. RESULTS: A total of 151 nerve fibers were recorded during dissection. The infratrochlear, supratrochlear, supraorbital, and lacrimal nerve contributed each to both the upper eyelid skin innervation and the upper eyelid rim plexus in different distribution patterns. The mean distance from the eyelid margin at which nerve fibers pierced from preseptal into the orbicularis muscle was 14 ± 1.1 mm for nerve fibers targeting the eyelid dermis and 3.7 ± 1.2 mm for nerve fibers targeting the eyelid rim plexus ( p < 0.001). The mean intraorbicular course of nerve fibers was 3 mm (0-17; standard deviation 4.1). The mean distance from the eyelid margin at which nerve fibers pierced from the orbicularis muscle into the preorbicular plane was 10 ± 1 mm for nerve fibers innervating the eyelid dermis and 1.3 ± 0.8 mm for nerve fibers innervating the eyelid rim plexus ( p < 0.001). The mean distance of the preorbicular course of nerve fibers was 2 mm (0-15; standard deviation 3.6). CONCLUSIONS: Based on the findings, a certain degree of postoperative eyelid skin numbness is inevitable while eyelash innervation may be spared in upper blepharoplasty.

Patient-Specific Guides for Accurate and Precise Positioning of Osseointegrated Implants in Transfemoral Amputations: A Proof-of-Concept In Vitro Study.

Background and Objectives: The treatment of transfemoral amputees using osseointegrated implants for prosthetic anchorage requires accurate implant positioning when using threaded bone-anchoring implants due to the curvature of the femur and the risk of cortical penetration in misaligned implants. This study investigated the accuracy and precision in implant positioning using additively manufactured case-specific positioning guides. Materials and Methods: The geometry and density distribution of twenty anatomic specimens of human femora were assessed in quantitative computed tomography (QCT) scanning. The imaging series were used to create digital 3D specimen models, preoperatively plan the optimal implant position and manufacture specimen-specific positioning guides. Following the surgical bone preparation and insertion of the fixture (threaded bone-anchoring element) (OPRA; Integrum AB, Mölndal, Sweden), a second QCT imaging series and 3D model design were conducted to assess the operatively achieved implant position. The 3D models were registered and the deviations of the intraoperatively achieved implant position from the preoperatively planned implant position were analyzed as follows. The achieved, compared to the planned implant position, was presented as resulting mean hip abduction or adduction (A/A) and extension or flexion (E/F) and mean implant axis offset in medial or lateral (M/L) and anterior or posterior (A/P) direction measured at the most distal implant axis point. Results: The achieved implant position deviated from the preoperative plan by 0.33 ± 0.33° (A/A) and 0.68 ± 0.66° (E/F) and 0.62 ± 0.55 mm (M/L) and 0.68 ± 0.56 mm (A/P), respectively. Conclusions: Using case-specific guides, it was feasible to achieve not only accurate but also precise positioning of the implants compared to the preoperative plan. Thus, their design and application in the clinical routine should be considered, especially in absence of viable alternatives.

Microsurgical transcranial approaches to the posterior surface of petrosal portion of the temporal bone: quantitative analysis of surgical volumes and exposed areas.

Different microsurgical transcranial approaches (MTAs) have been described to expose the posterior surface of the petrous bone (PPB). A quantitative, anatomical comparison of the most used MTAs, for specific areas of the PPB, is not available. Anatomical dissections were performed on five formalin-fixed, latex-injected cadaver heads (10 sides). Six MTAs were analyzed: Kawase approach (KWA), retrosigmoid approach (RSA), retrosigmoid approach with suprameatal extension (RSAS), retrolabyrinthine approach (RLA), translabyrinthine approach (TLA), and transcochlear approach (TCA). Surgical volumes and exposed areas of each approach were quantified with a dedicated neuronavigation system (ApproachViewer, part of GTx-Eyes II, University Health Network, Toronto, Canada) and adjuvant software (ITK-SNAP and Autodesk Meshmixer 3.5). Areas and volumes were compared using linear mixed models. TCA provided the best exposure of Trautmann's triangle and the retromeatal, suprameatal, meatal, and premeatal regions. RSAs provided the best exposure of the inframeatal region, with RSAS gaining significant exposure of the suprameatal region. KWA had the highest surgical volume, and RLA the lowest. Transpetrosal approaches offer the widest exposure of PPB proportionally to their invasiveness. Retrosigmoid approaches, which get to the studied region through a postero-lateral path, are paramount for the exposure of the inframeatal and suprameatal region and, given the adequate exposure of the remaining PPB, represent an effective approach for the cerebellopontine angle (CPA). These anatomical findings must be considered with approach-related morbidity and the pathological features in order to choose the most appropriate approach in clinical practice.

Influence of Scan Parameters of Single and Dual-Energy CT Protocols in Combination with Metal Artifact Suppression Algorithms for THA: An ex Vivo Study.

BACKGROUND: Metal artifacts caused by hip arthroplasty stems limit the diagnostic value of computed tomography (CT) in the evaluation of periprosthetic fractures or implant loosening. The aim of this ex vivo study was to evaluate the influence of different scan parameters and metal artifact algorithms on image quality in the presence of hip stems. METHODS: Nine femoral stems, 6 uncemented and 3 cemented, that had been implanted in subjects during their lifetimes were exarticulated and investigated after death and anatomical body donation. Twelve CT protocols consisting of single-energy (SE) and single-source consecutive dual-energy (DE) scans with and without an iterative metal artifact reduction algorithm (iMAR; Siemens Healthineers) and/or monoenergetic reconstructions were compared. Streak and blooming artifacts as well as subjective image quality were evaluated for each protocol. RESULTS: Metal artifact reduction with iMAR significantly reduced the streak artifacts in all investigated protocols (p = 0.001 to 0.01). The best subjective image quality was observed for the SE protocol with a tin filter and iMAR. The least streak artifacts were observed for monoenergetic reconstructions of 110, 160, and 190 keV with iMAR (standard deviation of the Hounsfield units: 151.1, 143.7, 144.4) as well as the SE protocol with a tin filter and iMAR (163.5). The smallest virtual growth was seen for the SE with a tin filter and without iMAR (4.40 mm) and the monoenergetic reconstruction of 190 keV without iMAR (4.67 mm). CONCLUSIONS: This study strongly suggests that metal artifact reduction algorithms (e.g., iMAR) should be used in clinical practice for imaging of the bone-implant interface of prostheses with either an uncemented or cemented femoral stem. Among the iMAR protocols, the SE protocol with 140 kV and a tin filter produced the best subjective image quality. Furthermore, this protocol and DE monoenergetic reconstructions of 160 and 190 keV with iMAR achieved the lowest levels of streak and blooming artifacts. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Distal Nerve Transfers in High Peroneal Nerve Lesions: An Anatomical Feasibility Study.

The peroneal nerve is one of the most commonly injured nerves of the lower extremity. Nerve grafting has been shown to result in poor functional outcomes. The aim of this study was to evaluate and compare anatomical feasibility as well as axon count of the tibial nerve motor branches and the tibialis anterior motor branch for a direct nerve transfer to reconstruct ankle dorsiflexion. In an anatomical study on 26 human body donors (52 extremities) the muscular branches to the lateral (GCL) and the medial head (GCM) of the gastrocnemius muscle, the soleus muscle (S) as well as the tibialis anterior muscle (TA) were dissected, and each nerve's external diameter was measured. Nerve transfers from each of the three donor nerves (GCL, GCM, S) to the recipient nerve (TA) were performed and the distance between the achievable coaptation site and anatomic landmarks was measured. Additionally, nerve samples were taken from eight extremities, and antibody as well immunofluorescence staining were performed, primarily evaluating axon count. The average diameter of the nerve branches to the GCL was 1.49 ± 0.37, to GCM 1.5 ± 0.32, to S 1.94 ± 0.37 and to TA 1.97 ± 0.32 mm, respectively. The distance from the coaptation site to the TA muscle was 43.75 ± 12.1 using the branch to the GCL, 48.31 ± 11.32 for GCM, and 19.12 ± 11.68 mm for S, respectively. The axon count for TA was 1597.14 ± 325.94, while the donor nerves showed 297.5 ± 106.82 (GCL), 418.5 ± 62.44 (GCM), and 1101.86 ± 135.92 (S). Diameter and axon count were significantly higher for S compared to GCL as well as GCM, while regeneration distance was significantly lower. The soleus muscle branch exhibited the most appropriate axon count and nerve diameter in our study, while also reaching closest to the tibialis anterior muscle. These results indicate the soleus nerve transfer to be the favorable option for the reconstruction of ankle dorsiflexion, in comparison to the gastrocnemius muscle branches. This surgical approach can be used to achieve a biomechanically appropriate reconstruction, in contrast to tendon transfers which generally only achieve weak active dorsiflexion.

Clinical Applicability of the Sellar Barrier Concept in Patients with Pituitary Apoplexy: Is It Possible?

There is evidence of association between sellar barrier thickness and intraoperative cerebrospinal fluid (CSF) leakage, impacting the postoperative prognosis of the patients. The aim of this study is to analyze the clinical applicability of the sellar barrier concept in a series of operated patients with pituitary apoplexy (PA). A retrospective study was conducted including 47 patients diagnosed with PA who underwent surgical treatment through a transsphenoidal approach. Brain magnetic resonance imaging (MRI) of the patients were evaluated and classified utilizing the following criteria: strong barrier (greater than 1 mm), weak barrier (less than 1 mm), and mixed barrier (less than 1 mm in one area and greater than 1 mm in another). The association between sellar barrier types and CSF leakage was analyzed, both pre- and intraoperatively. The preoperative MRI classification identified 10 (21.28%) patients presenting a weak sellar barrier, 20 patients (42.55%) with a mixed sellar barrier, and 17 patients (36.17%) exhibiting a strong sellar barrier. Preoperative weak and strong sellar barrier subtypes were associated with weak (p ≤ 0.001) and strong (p = 0.009) intraoperative sellar barriers, respectively. Strong intraoperative sellar barrier subtypes reduced the odds of CSF leakage by 86% (p = 0.01). A correlation between preoperative imaging and intraoperative findings in the setting of pituitary apoplexy has been observed.